Airplane propeller



Aug. ,21, 1934. o. 1., GIBBS f 1,970,847-

AIRPLANE PROPELLER Filed Feb. 11, 1932 2 Sheets-Sheet 1 INVENTOR. 4

ATTORNEY.

Aug. 21, 1934. o. LQGIBBS 1,970,847

AIRPLANE PROFELLER Filed Feb. 11, 1932 2 Sheets-Sheet 2 I N VEN TOR.

ATTORNEY.

mm A. 67%.;

Patented Aug. 21, 1934 I e UNITED STATES PATENT orrlcs" AIRPLANE PROPELLER Orma L. Gibbs, Kansas City, Mo., asslgnor of file-half to Eugene B. Berkowitz Kansas City,

Application February 11, 1932, No. 592,276 2 Claims. (Cl. 170-162) My invention relates to propellers and par- 14. The spring 14 is coiled about the shaft and ticularly to those of that character adapted for has one end engaging againstthe collar and its airplane use, and has for its principal object to other end against the end of the shank whereby provide for automatically changing the effective the shaft is normally retained in retracted posi- 5 pitch of the propeller blades proportional to the tion with the rear end thereof in engagement varying load conditions acting thereon. with a stop member located in the rear, end of In accomplishing this and other objects of the the bore. The stop member may be a pin, such invention, I have provided improved details of as shown, having its ends anchored in the body structure, the preferred form of which is illusportion of the hub, or the end of the bore may 10 trated in the accompanying drawings, wherein: be closed as desired.

Fig. 1 is a perspective view of a propeller em- Formed in the hub and extending at right bodying my invention and illustrating the posiangles to thebore are spaced, parallel bores 16 tion of the blades when the propeller is at rest and 17 having their. peripheries intersecting the or operating under minimum load conditions. bore 6 on opposite diametrical sides thereof.

Fig. 2 is a similar view of the propeller illus- The ends of the bores 16 and l'l'are preferably 70 trating position of the blades when the propeller counterbored to provide races for anti-friction is operating under its maximum load conditions. bearings 18 and 19 which mount the spindles Fig. 3 is a sectional view through one of the 20-and 21 of propeller blades 23 and 2.4 now blades on the line 3-3, of Fig. 2, illustrating described.

0 minimum pitch of the blades-in full lines and The propeller blades are of novel shape, hav- 75 maximum pitch in dotted lines. ing relatively narrow tips 25 gradually widen- Fig. 4 is a longitudinal sectional view through ing toward the hub. The forward edges of the the propeller hub illustrating position of the blades 26 are stream lined and extend parallel control parts when the blades are operating with each other and tangentially to a circle 5 under minimum load conditions. having its center concentric with the axis of 8 Fig. 5 is a similar view illustrating the control the bore 6, whereby the blades are positioned parts when the. blades are operating under maxto counter-balance each other at the opposite imum load conditions. sides of the hub. The trailing edges 28 of the Fig. 6 is a cross sectional view through the blades are curved rearwardly and laterally of hub illustrating mounting of Y the blades in the their forward edges to provide the desired shape, hub. I and form concaves 29 extending longitudinally Referring more in detail to the drawings: of their rear faces and corresponding convex 1 designates the propeller hub which, in the surfaces 30 on their outer faces. form illustrated, includes a substantially rec- Extending from the inner ends of the blades 35 tangular body having an integral socket portion are the spindles 20 and 21 having reduced ends 2 on its rear face whereby the propeller may 31 to accommodatethe diameter of the bores be mounted on its operating shaft (not shown) and to f'orm'bearing races 32 adjacent the base in any suitable manner, and having a boss 3 on of the blades for the bearin e 19- h its front face for mounting the usual spinner t e Outer ds of the Spindles are further 40 4 and adjusting nut 5 later described. Extendduced adjacent the other set of bearing races ing axially through the hub and through th 18 to form races 33. The intermediate portion boss 3 is a cylindrical bore 6 for housing a, reof the spin a P vided with longitudinal ciprocable blade control shaft '7. grooves at equally spaced intervals about their The shaft 7 has a head portion 8 provided P p y to P e teeth 3 or en the 45 with series of spaced circumferential i 9 teeth on the control shaft previously described.

forming. rack teeth for a purpose later described. In Order to retain the Spindles against 8 Formed on the shaft adjacent the foremost rib tudinal movement in t hu the ends thereof is a collar 10 for guiding and retaining the shaft are drilled and tappe as t 5 t0 flcwmmodate concentrically of the bore. The forward end of screws 36 for securing cone-shaped disks 37 en- 0 the shaft is slidably supported in a bore 11 of easin a ainst the bearin e 18. The p ndl s the adjusting nut 5 previously mentioned. are thus rotatably retained between the beare mi 5 inc udes a p y o ped head ings but their degree of rotation is under con- 12 and a threaded shank 13 that is threaded trol of the spring 14 as hereinafter described into the forward end of the bore 6 to close the in the operation of the propeller. 5 open end thereof and load an expansion spring In assembling the propeller constructed as described, the spindles are mounted in opposite sides of the hub and are secured by the cone disks 3'7 and screws 36 which may be locked by suitable lock pins or the like to prevent their retractive rotation during movement of the blades.

The shaft 7 is then inserted in the bore so that the ribs 9 engage between the teeth on the spindles and. theend thereof engages the stop pin. The'spring 14 is then sleeved over the protruding end of the shaft. The spinner 4 is applied to the threaded shank 13 of the adjusting nut and the shank is threaded into the bore to load the spring, after which the spinner may be rotated on the threads to engage the end of the boss 3 to form a lock for the adjusting nut.

It is thus apparent that the spring resists rotary movementof the blades so that the blades are normally retained in the position as shown in Fig. 1 when the propeller is operating under minimum load conditions, which is the maximum pitch of the propeller.

When the load'conditions increase, resistance on the blades causes them to rotate in the hub to automatically reduce their pitch. For example, assuming that the propeller is applied to an airplane and the propeller is idling preparatory to the start of a flight, the spring 14 retains the blades at their maximum pitch. But as soon as the speed of the propeller is increased the air load on the blades correspondingly increases until the load begins to exceed the load of the spring, tending to keep the blades in retracted position. The spring therefore yields to' the load and permits automatic reduction in the effective pitch of the propeller proportionate to the increase of the load. As soon as the plane attains its normal speed and elevation, the load resistance on the propeller becomes less so that the spring again preponderates to automatically shift the control shaft rearwardly to cause the teeth thereon to rotate the blade spindles in the opposite direction, thereby increasing the effective pitch of the propeller. Y

Itis, therefore, apparent that the load on the motor of the airplane may be retained within its rated power by. adjusting tension of the spring 14, by'means of the adjusting nut. By thus automatically controlling the pitch of the propeller while in flight it is substantially impossible to stall the motor, due to the aviator placing his controls in such a position that the power required to effect elevation exceeds the power of the motor because the pitch of the blades is automatically reduced to compensate for the sudden additional load on the motor by decreasing therate of climb.

The propeller thus provides a safety factor because its automatic control assures suflicient motor power to raise the plane from the ground and also enables a high speed of the plane as soon as the abnormal loads are reduced when the plane has attained its elevation.

While I have illustrated my invention as applied to airplane propellers, it is obvious that all proportionate to the load being moved thereby.

What I claim and desire to secure by Letters Patent is:

1. In a propeller of the character described, a hub having an axial bore and parallel lateral bores extending through the hub substantially tangentially with opposite diametrical sides of the axial bore and intersecting therewith, spindles rotatably supported in the lateral bores, propeller blades carried by the spindles and having greater areas lying to the rear of the axes of the spindles and adapted to move upon rotation of the spindles toward and from a common transverse plane extending through the axes of the spindles, stop means in one end of the axial bore, an adjusting member in the opposite .end of the bore, a control shaft provided with a spring seat portion and slidable in the bore and having teeth engaging with the teeth on the spindles, and a spring coiled about the spindles whereby the effective pitch of the propeller blades is controlled by the load acting thereon.

2. In a propeller of the character described, a hub having an axial bore and parallel lateral bores extending through the hub substantially tangentially with opposite diametrical sides of the axial bore and intersecting therewith. two spindles rotatably supported in the lateral bores, propeller blades carried by the spindles and having greater areas lying to the rear of the axes of the spindles and adapted to move upon rotation of the spindles toward and from a common transverse plane extending through the axes of the spindles, stop means in one end of the axial bore, an adjusting member in the opposite end of the bore, a control shaft provided with a spring seat portion and slidable in the bore and having, teeth engaging with the teeth on the spindles, a spring coiled about the control shaft and having one end engaging said spring seat portion and its opposite end engaging said adjusting member to normally retain the control shaft in engagementwith said stop means when the greater areas of said blades approach said plane and to resist longitudinal movement of the control shaft away from said stop means proportional to the load acting on said areas of the blades tending to rotate said spindles whereby the effective pitch of the propeller blades is controlled by the load acting thereon, and a spinner member threaded on said adjusting member and engagingthe hub to lock said adjusting member, in adjusted position.

' ORMA L. GIBBS. 

